76 PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
memoir. Thus, speaking of Sphenophyllum, the “ Commissaires ” say “ La structure 
interne de ces parties indique les rapports de ces vegetaux avec les Lycopodiacees et les 
Marsileacees” The report then proceeds to examine certain spikes of fructification, 
including those described by M. Ludwig and Mr. Bimey. Speaking of the fruit associated 
by the latter author with Calamodendron commune, the report remarks II reste 
Dependant encore bien des doutes it eclaircir; si les epis de fructification d'Autun 
appartient, sans aucun doute au x Annularia, ceux decnts par MM. Ludwig et Binney 
sont-ils reellement des fructifications, soit de Calamites, soit de Calamodendron% Ne 
se rapporteraient-ils pas plutot a des Sphenophyllum, dont ils se rapprochent par le 
nombre moindre des organes verticilles, et d’apres les figures de M. Binrey, par tear 
axe plus grele et yasculaire dans son centre?” In making the above and other com- 
parisons contained in the “Rapport,” M. Brongkiart has overlooked my still more 
significant Vollcmamia Dawsoni. I can only conclude that the disturbances occasioned 
by the war have prevented him from receiving the copy of the memoir which I sent 
to him. ,,, 
I have again to acknowledge my obligations to Messrs. Butteeworth, Whittaker, 
and Nield for their valuable assistance in procuring specimens for my investigation from 
the Oldham district, and to G. Grieve, Esq., for aiding me in like manner with examples 
from those Burntisland beds which the right of discovery has made so peculiarly his own. 
I may further observe, in reference to the Plates illustrating this memoir, that having 
made every drawing myself with the most scrupulous care, upon lithographic paper, so 
that they reappear in the Plates exactly as they left my hands, they may be relied upon 
as faithful transcripts of the objects represented. 
TAs this memoir is passing through the press I have received from M. Renault a copy 
of his valuable memoir entitled “ Recherches sur l’organisation des Sphenophyllum et des 
Annularia, ,” the publication of which has been delayed through the disturbances occa- 
sioned by the war. It demonstrates most clearly the very close general resemblances 
existing between his specimens of Sphenophyllum and mine of Asterophylhtes. But 
there is one singular difference. In the French specimens, the zone corresponding with 
my exogenous zone, and of which the transverse sections correspond in the most minute 
manner with my figures 3, 4, & 9, chiefly consists not of long vessels, but of cubical cells 
arranged in vertical piles. Like my vessels, the walls of these cells are beautifully 
reticulated. It appears as if these cells were arranged in vertical lines preparatory to 
their coalescence and conversion into vessels, but that this double process had never 
taken place. This substitution of remarkably distinct reticulated cells for equally 
distinct reticulated vessels is a curious physiological fact. It is also perfectly clear that 
the vessels given off to supply the leaves in the French examples spring from the central 
triangular axis, and not from the exogenous layers, as I have already pointed out m the 
note on page 45, the former having been the primary vascular bundle of the young shoot. 
On the other hand, the vascular bundles given off to the rootlets evidently spring, not 
from the triangular axes of the roots, but from the exogenous layer. These arrange- 
